Post combustion carbon capture plants, or plants for capturing CO2 from an exhaust gas from an industrial plant, such as a thermal power plant producing electrical power and/or heat by combustion of carbonaceous fuels, are physically large constructions due to the volume of exhaust gas to be treated.
An absorption column for a 400 MW gas fired power plant has typically an absorber having a cross section of more than 300 m2, and a height of 50-60 meters. Due to the size thereof, concrete is a building material of interest, as large constructions like such an absorber may be built at a reasonable cost and will have an acceptable life expectancy.
To provide a life expectancy of 30 years or more, which is the normal requirement set for such plants, the inner walls of the absorption column, is normally to be lined with a protecting liner, such as a liner of polymer material. A liner of a polymer material, such as a polyolefin, will normally be produced in panels that welded together to make up a watertight inner wall of the column. Apertures in the inner liner wall are made watertight by welding liners into tubing and other apertures connected to the inner of the absorber column.
In the casting process, slip form will normally be used, as this is an efficient and cost effective way of constructing such a column. The lining may then be a part of or all of the inner formwork that will remain in the position after the finishing of the slip form. Preferably, anchors are present on the surface of the liner panels facing the concrete to anchor the panels to the concrete surface.
Leakage may, however, occur in the liner, caused either by welding defects, damages or by physical stress to parts of the liner. The absorbent used in CO2 capture plants is normally an aqueous solution of one or more chemicals absorbing CO2, such as amine(s). If leakages occur, the aqueous solution will enter into a narrow, and possibly imperfect, space formed between the concrete surface and the liner. The aqueous solution will trickle downwards. Since there is no bond between the lining and the concrete surface, projections as corbels will not stop the solution to continue to the bottom floor level.
As soon as the tickling liquid is stopped by meeting the bottom of the absorber column or any other means stopping the liquid to tickle downwards, a liquid column of substantial height may be build up between the concrete wall and the liner, a liquid column that may cause a substantial force separating the concrete wall and the liner. This separating force may break the anchorage between the concrete wall and the liner and may eventually cause the liner to break into the column, as there is no counterforce preventing this.
U.S. Pat. No. 5,248,220 relates to a liner sheet, liner panel system and a method for making the same that provides continuous passages between the liner and a lined liquid containment structure, such as a tank, towers, sewage pipes etc., for detection of leakage and for draining leakage by providing a sensor in a drainage tube. Drainage tubes are provided through the walls of the walls of the structure.
DE 4232493 relates to a lined concrete or steel tank, and a method for production of the same. Any liquid leaked into the space between the lining and the tank is drained into channels below the bottom part of the tank.
Large tanks or towers for chemical processes made of concrete is often produced by slide moulding, i.e. a moulding process where cement is substantially continuously poured onto the top of a casting mould, and where the casting mould is slided upwards as the cement at the lower part thereof is set. The above identified prior art is silent how to provide drainage tubes through cement walls in the casting process.
An object of the present invention is therefore to provide a method for providing a fluid connection from the space between a lining and walls of a lined tank, column, tower or the like, for detection of liquid leakage through the lining and for drainage of any liquid trapped between the lining and the walls.
Another object is to provide a method and device for detecting leakage of absorbent from the inner of an absorber tower into the space between the inner walls of an absorber tower and a liner, to be able to detect and localize a leakage to be able to consider a time for doing a repair, and to identify which part of the column the leakage is situated.